Abstract: A toilet such as used with a recreational vehicle, camper or motor home or the like includes a holding tank located beneath the toilet for holding waste. A mechanical seal associated with the toilet prevents gases from the holding tank from entering the room where the toilet is located. The mechanical seal which must be opened periodically when the toilet is used activates a fan in the sanitary system ventilation piping to thereby cause air to flow from the room into the toilet and through the holding tank and ventilation system to the outside atmosphere. A strainer or screen which may be located either between the toilet opening and the vent opening in the tank or further upstream of the ventilation fan prevents solids from being drawn into the vent piping and operating mechanism, respectively. A mist extractor chamber upstream of the fan in the vent piping removes vapors from the flow of gases. Also to clean the vent pipe a cleanout and purge fitting is installed there.